I use it to take photographs of group work and upload to the site for future reference. This could be used as part of a homework task, for example, then using googledocs to create a collaborative powerpoint.
An app is available on iPhone or Android (click on relevant phone type to be taken to the website to download the app; it's FREE).
This allow you to upload up to 10 photos at a time directly to your flickr account (you have to initially sign up - this only takes a couple of minutes).
You can then create a link to that site for pupils to access. I leave it viewable to anyone so they don't need to log in to see it.
I use bit.ly to shorten links and make them easy for pupils to copy down or remember: http://bit.ly/int2pics is a link to my flickr stream.
Click on bit.ly for more information on how to use it.
An online photo-sharing site.
http://bit.ly/int2pics